阅读webpack代码笔记：antd-layout的webpack.config.prod.js

 'use strict';

 const autoprefixer = require('autoprefixer');//自动补全css前缀
 const path = require('path');
 const webpack = require('webpack');
 //自动生成带有入口文件引用的index.html
 const HtmlWebpackPlugin = require('html-webpack-plugin');
 //ExtractTextPlugin将所有的入口 chunk(entry chunks)中引用的 *.css，移动到独立分离的 CSS 文件
 const ExtractTextPlugin = require('extract-text-webpack-plugin');
 //ManifestPlugin用于生成manifest.json
 const ManifestPlugin = require('webpack-manifest-plugin');
 //InterpolateHtmlPlugin:和HtmlWebpackPlugin串行使用，允许在index.html中添加变量
 const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
 //用于使用service worker来缓存外部项目依赖项。 它将使用sw-precache生成service worker文件并将其添加到您的构建目录
 const SWPrecacheWebpackPlugin = require('sw-precache-webpack-plugin');
 const eslintFormatter = require('react-dev-utils/eslintFormatter');
 const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
 const paths = require('./paths'); //获取paths对象
 const getClientEnvironment = require('./env');

 // Webpack uses `publicPath` to determine where the app is being served from.
 // It requires a trailing slash, or the file assets will get an incorrect path.
 const publicPath = paths.servedPath; //package.json所在的路径
 // Some apps do not use client-side routing with pushState.
 // For these, "homepage" can be set to "." to enable relative asset paths.
 const shouldUseRelativeAssetPaths = publicPath === './';
 // Source maps are resource heavy and can cause out of memory issue for large source files.
 const shouldUseSourceMap = process.env.GENERATE_SOURCEMAP !== 'false';
 // `publicUrl` is just like `publicPath`, but we will provide it to our app
 // as %PUBLIC_URL% in `index.html` and `process.env.PUBLIC_URL` in JavaScript.
 // Omit trailing slash as %PUBLIC_URL%/xyz looks better than %PUBLIC_URL%xyz.
 const publicUrl = publicPath.slice(0, -1);
 // Get environment variables to inject into our app.
 const env = getClientEnvironment(publicUrl);

 // Assert this just to be safe.
 // Development builds of React are slow and not intended for production.
 if (env.stringified['process.env'].NODE_ENV !== '"production"') {
     throw new Error('Production builds must have NODE_ENV=production.');
 }

 // Note: defined here because it will be used more than once.
 const cssFilename = 'static/css/[name].[contenthash:8].css';

 // ExtractTextPlugin expects the build output to be flat.
 // (See https://github.com/webpack-contrib/extract-text-webpack-plugin/issues/27)
 // However, our output is structured with css, js and media folders.
 // To have this structure working with relative paths, we have to use custom options.
 const extractTextPluginOptions = shouldUseRelativeAssetPaths
         ? // Making sure that the publicPath goes back to to build folder.
         { publicPath: Array(cssFilename.split('/').length).join('../') }
         : {};

 // This is the production configuration.
 // It compiles slowly and is focused on producing a fast and minimal bundle.
 // The development configuration is different and lives in a separate file.

 module.exports = {
     // Don't attempt to continue if there are any errors.
     bail: true,
     // We generate sourcemaps in production. This is slow but gives good results.
     // You can exclude the *.map files from the build during deployment.
     devtool: shouldUseSourceMap ? 'source-map' : false,
     // In production, we only want to load the polyfills and the app code.
     entry:{        // require.resolve('./polyfills'),
         //paths.appIndexJs ,
         app:paths.appIndexJs , //src/index.js
         vendor:[ //把引用react的类提取出公共模块
           'react',
           'react-dom',
           'react-router'
         ],
         antd:[ //提取ant到公共模块
            'antd/lib/button',
            'antd/lib/icon'
          //'antd'
         ]
     },
     output: {
         // The build folder.
         path: paths.appBuild,
         // Generated JS file names (with nested folders).
         // There will be one main bundle, and one file per asynchronous chunk.
         // We don't currently advertise code splitting but Webpack supports it.
         filename: 'static/js/[name].[chunkhash:8].js',
         chunkFilename: 'static/js/[name].[chunkhash:8].chunk.js',
         // We inferred the "public path" (such as / or /my-project) from homepage.
         publicPath: publicPath,
         // Point sourcemap entries to original disk location (format as URL on Windows)
         devtoolModuleFilenameTemplate: info =>
                 path
                         .relative(paths.appSrc, info.absoluteResourcePath)
                         .replace(/\\/g, '/'),
     },
     resolve: {//这些选项能设置模块如何被解析
         // This allows you to set a fallback for where Webpack should look for modules.
         // We placed these paths second because we want `node_modules` to "win"
         // if there are any conflicts. This matches Node resolution mechanism.
         // https://github.com/facebookincubator/create-react-app/issues/253
         //modules告诉 webpack 解析模块时应该搜索的目录
         modules: ['node_modules', paths.appNodeModules].concat(
                 // It is guaranteed to exist because we tweak it in `env.js`
                 process.env.NODE_PATH.split(path.delimiter).filter(Boolean)
         ),
         // These are the reasonable defaults supported by the Node ecosystem.
         // We also include JSX as a common component filename extension to support
         // some tools, although we do not recommend using it, see:
         // https://github.com/facebookincubator/create-react-app/issues/290
         // `web` extension prefixes have been added for better support
         // for React Native Web.
         //extensions:自动解析确定的扩展
         extensions: ['.web.js', '.mjs', '.js', '.json', '.web.jsx', '.jsx'],
         //alias: 创建 import 或 require 的别名
         alias: {

             // Support React Native Web
             // https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
             'react-native': 'react-native-web',
         },
         //plugin:应该使用的额外的解析插件列表
         plugins: [
             // Prevents users from importing files from outside of src/ (or node_modules/).
             // This often causes confusion because we only process files within src/ with babel.
             // To fix this, we prevent you from importing files out of src/ -- if you'd like to,
             // please link the files into your node_modules/ and let module-resolution kick in.
             // Make sure your source files are compiled, as they will not be processed in any way.
             new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson]),
         ],
     },
     //module:这些选项决定了如何处理项目中的不同类型的模块
     module: {
         strictExportPresence: true,
         //每个规则可以分为三部分 - 条件(condition)，结果(result)和嵌套规则(nested rule)
         //创建模块时，匹配请求的规则数组。这些规则能够修改模块的创建方式。这些规则能够对模块(module)应用 loader，或者修改解析器(parser)。
         rules: [
             // TODO: Disable require.ensure as it's not a standard language feature.
             // We are waiting for https://github.com/facebookincubator/create-react-app/issues/2176.
             // { parser: { requireEnsure: false } },

             // First, run the linter.
             // It's important to do this before Babel processes the JS.
             {
                 //test:匹配特定条件。一般是提供一个正则表达式或正则表达式的数组，但这不是强制的
                 test: /\.(js|jsx|mjs)$/,
                 enforce: 'pre',
                 // use: [
                 //     {
                 //         options: {
                 //             formatter: eslintFormatter,
                 //             eslintPath: require.resolve('eslint'),

                 //         },
                 //         loader: require.resolve('eslint-loader'),
                 //     },
                 // ],
                 //loader是文件预处理器
                 //使用babel-loader加载js,jsx,mjs
                 //babel-loader用来处理ES6语法，将其编译为浏览器可以执行的js语法
                 loader: require.resolve('babel-loader'), //resolve返回绝对路径
                 include: paths.appSrc,
             },
             {
                 // "oneOf" will traverse all following loaders until one will
                 // match the requirements. When no loader matches it will fall
                 // back to the "file" loader at the end of the loader list.
                 //oneOf:当规则匹配时，只使用第一个匹配规则
                 oneOf: [
                     // "url" loader works just like "file" loader but it also embeds
                     // assets smaller than specified size as data URLs to avoid requests.
                     {
                         test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
                         loader: require.resolve('url-loader'),
                         options: {
                             limit: 10000,
                             name: 'static/media/[name].[hash:8].[ext]',
                         },
                     },
                     // Process JS with Babel.
                     {
                         test: /\.(js|jsx|mjs)$/,
                         include: paths.appSrc,
                         loader: require.resolve('babel-loader'),
                         // options: {
                         //     plugins: [
                         //         ['import', [{ libraryName: "antd", style: 'css' }]],
                         //     ],
                         //     compact: true,
                         // },
                     },
                     // The notation here is somewhat confusing.
                     // "postcss" loader applies autoprefixer to our CSS.
                     // "css" loader resolves paths in CSS and adds assets as dependencies.
                     // "style" loader normally turns CSS into JS modules injecting <style>,
                     // but unlike in development configuration, we do something different.
                     // `ExtractTextPlugin` first applies the "postcss" and "css" loaders
                     // (second argument), then grabs the result CSS and puts it into a
                     // separate file in our build process. This way we actually ship
                     // a single CSS file in production instead of JS code injecting <style>
                     // tags. If you use code splitting, however, any async bundles will still
                     // use the "style" loader inside the async code so CSS from them won't be
                     // in the main CSS file.
                     {//定义如何加载css，scss,如果需要解析less要再次配置
                         test: /\.(css|scss|styl)$/,
                         loader: ExtractTextPlugin.extract(
                                 Object.assign(
                                         {
                                             fallback: {
                                                 loader: require.resolve('style-loader'),
                                                 options: {
                                                     hmr: false,
                                                 },
                                             },
                                             use: [
                                                 {
                                                     loader: require.resolve('css-loader'),
                                                     options: {
                                                         importLoaders: 1,
                                                         minimize: true,
                                                         sourceMap: shouldUseSourceMap,
                                                     },
                                                 },
                                                 {
                                                     loader: require.resolve('postcss-loader'),
                                                     options: {
                                                         // Necessary for external CSS imports to work
                                                         // https://github.com/facebookincubator/create-react-app/issues/2677
                                                         ident: 'postcss',
                                                         plugins: () => [
                                                             require('postcss-flexbugs-fixes'),
                                                             autoprefixer({
                                                                 browsers: [
                                                                     '>1%',
                                                                     'last 4 versions',
                                                                     'Firefox ESR',
                                                                     'not ie < 9', // React doesn't support IE8 anyway
                                                                 ],
                                                                 flexbox: 'no-2009',
                                                             }),
                                                         ],
                                                     },
                                                 },
                                                 {
                                                     loader: require.resolve('sass-loader') // compiles Less to CSS
                                                 },
                                                 {
                                                     loader: require.resolve('stylus-loader') // compiles stylus to CSS
                                                 }
                                             ],
                                         },
                                         extractTextPluginOptions
                                 )
                         ),
                         // Note: this won't work without `new ExtractTextPlugin()` in `plugins`.
                     },
                     // "file" loader makes sure assets end up in the `build` folder.
                     // When you `import` an asset, you get its filename.
                     // This loader doesn't use a "test" so it will catch all modules
                     // that fall through the other loaders.
                     {
                         loader: require.resolve('file-loader'),
                         // Exclude `js` files to keep "css" loader working as it injects
                         // it's runtime that would otherwise processed through "file" loader.
                         // Also exclude `html` and `json` extensions so they get processed
                         // by webpacks internal loaders.
                         exclude: [/\.(js|jsx|mjs)$/, /\.html$/, /\.json$/],
                         options: {
                             name: 'static/media/[name].[hash:8].[ext]',
                         },
                     },
                     // ** STOP ** Are you adding a new loader?
                     // Make sure to add the new loader(s) before the "file" loader.
                 ],
             },
         ],
     },
     //plugins定义使用的插件
     plugins: [
         new HelloWorldPlugin(),
         // Makes some environment variables available in index.html.
         // The public URL is available as %PUBLIC_URL% in index.html, e.g.:
         // <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
         // In production, it will be an empty string unless you specify "homepage"
         // in `package.json`, in which case it will be the pathname of that URL.
         new InterpolateHtmlPlugin(env.raw),
         // Generates an `index.html` file with the <script> injected.
         new HtmlWebpackPlugin({
             inject: true,
             template: paths.appHtml,
             minify: {
                 removeComments: true,
                 collapseWhitespace: true,
                 removeRedundantAttributes: true,
                 useShortDoctype: true,
                 removeEmptyAttributes: true,
                 removeStyleLinkTypeAttributes: true,
                 keepClosingSlash: true,
                 minifyJS: true,
                 minifyCSS: true,
                 minifyURLs: true,
             },
         }),
         //CommonsChunkPlugin，用于抽离代码
         new webpack.optimize.CommonsChunkPlugin({
           names: ['antd', 'vendor'],
           minChunks: Infinity
         }),
         // Makes some environment variables available to the JS code, for example:
         // if (process.env.NODE_ENV === 'production') { ... }. See `./env.js`.
         // It is absolutely essential that NODE_ENV was set to production here.
         // Otherwise React will be compiled in the very slow development mode.
         new webpack.DefinePlugin(env.stringified),
         // Minify the code.
         new webpack.optimize.UglifyJsPlugin({
             compress: {
                 warnings: false,
                 // Disabled because of an issue with Uglify breaking seemingly valid code:
                 // https://github.com/facebookincubator/create-react-app/issues/2376
                 // Pending further investigation:
                 // https://github.com/mishoo/UglifyJS2/issues/2011
                 comparisons: false,
             },
             mangle: {
                 safari10: true,
             },
             output: {
                 comments: false,
                 // Turned on because emoji and regex is not minified properly using default
                 // https://github.com/facebookincubator/create-react-app/issues/2488
                 ascii_only: true,
             },
             sourceMap: shouldUseSourceMap,
         }),
         // Note: this won't work without ExtractTextPlugin.extract(..) in `loaders`.
         new ExtractTextPlugin({
             filename: cssFilename,
         }),
         // Generate a manifest file which contains a mapping of all asset filenames
         // to their corresponding output file so that tools can pick it up without
         // having to parse `index.html`.
         new ManifestPlugin({
             fileName: 'asset-manifest.json',
         }),
         // Generate a service worker script that will precache, and keep up to date,
         // the HTML & assets that are part of the Webpack build.
         new SWPrecacheWebpackPlugin({
             // By default, a cache-busting query parameter is appended to requests
             // used to populate the caches, to ensure the responses are fresh.
             // If a URL is already hashed by Webpack, then there is no concern
             // about it being stale, and the cache-busting can be skipped.
             dontCacheBustUrlsMatching: /\.\w{8}\./,
             filename: 'service-worker.js',
             logger(message) {
                 if (message.indexOf('Total precache size is') === 0) {
                     // This message occurs for every build and is a bit too noisy.
                     return;
                 }
                 if (message.indexOf('Skipping static resource') === 0) {
                     // This message obscures real errors so we ignore it.
                     // https://github.com/facebookincubator/create-react-app/issues/2612
                     return;
                 }
                 console.log(message);
             },
             minify: true,
             // For unknown URLs, fallback to the index page
             navigateFallback: publicUrl + '/index.html',
             // Ignores URLs starting from /__ (useful for Firebase):
             // https://github.com/facebookincubator/create-react-app/issues/2237#issuecomment-302693219
             navigateFallbackWhitelist: [/^(?!\/__).*/],
             // Don't precache sourcemaps (they're large) and build asset manifest:
             staticFileGlobsIgnorePatterns: [/\.map$/, /asset-manifest\.json$/],
         }),
         // Moment.js is an extremely popular library that bundles large locale files
         // by default due to how Webpack interprets its code. This is a practical
         // solution that requires the user to opt into importing specific locales.
         // https://github.com/jmblog/how-to-optimize-momentjs-with-webpack
         // You can remove this if you don't use Moment.js:
         new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
     ],
     // Some libraries import Node modules but don't use them in the browser.
     // Tell Webpack to provide empty mocks for them so importing them works.
     node: {
         dgram: 'empty',
         fs: 'empty',
         net: 'empty',
         tls: 'empty',
         child_process: 'empty',
     },
 };